Electroporation, which is also known as electropermeabilization, involves a significant increase in electrical conductivity and permeability of the cell plasma semi-permeable membrane which is caused by applying an electric field to an area of a patient's body desired to be treated. Ordinarily, electroporation is used in molecular biology to introduce a substance inside the cell, such as loading it with a molecular probe, a drug that can change the cell's function or a piece of coding DNA. An unnatural increase in permeability is usually explained as a process of formation of very small openings (pores) in the plasma membrane, which increases the body's ability to absorb the therapeutic agent. If the strength of the electrical field and duration of exposure to it are properly chosen, the pores formed by the electrical pulse reseal after a short period of time, during which the extracellular compounds are better able to get inside the cell. A device that would evenly distribute a drug or therapeutic fluid to a specific internal anatomical location within a patient's body at a controlled rate that could also accurately apply an electric field to increase the permeability of the intended tissue would be extremely desirable.
Hollow fibers are made from porous polymers that were developed to improve the distribution of drugs administered directly into the central nervous system. It has been found that using a porous polymer hollow fiber significantly increases the surface area of brain tissue that the drug or therapeutic fluid is infused into. Dye was infused into a mouse brain by convection-enhanced delivery using a 28 gauge needle compared to a hollow fiber having a 3 mm length. Hollow fiber mediated infusion increased the volume of brain tissue labeled with dye by a factor of 2.7 times compared to using a conventional needle. In order to determine if hollow fiber use could increase the distribution of gene therapy vectors, a recombinant adenovirus expressing the firefly luciferase reporter was injected into the mouse striatum. Gene expression was monitored using in vivo luminescent imaging. In vivo imaging revealed that hollow fiber mediated infusion of adenovirus resulting in gene expression that was an order of magnitude greater than when a conventional needle was used for delivery. To assess distribution of gene transfer, an adenovirus expression green fluorescent protein was injected into the striatum using a hollow fiber and a conventional needle. The hollow fiber greatly increased the area of brain transduced with adenovirus relative to a needle, transducing a significant portion of the injected hemisphere.